Medical treatment often requires the administration of a therapeutic agent to a particular part of a patient's body. Some maladies, however, are difficult to treat with currently available therapies and/or require administration of drugs to anatomical regions which are difficult to access. A patient's eye is a prime example of a difficult-to-reach anatomical region, and conventional approaches to treating many vision-threatening diseases, including retinitis pigmentosa, age-related macular degeneration (AMD), diabetic retinopathy, and glaucoma, have associated complications. For example, oral medications can have systemic side effects; topical applications may sting and engender poor patient compliance; injections generally require a medical visit, can be painful, and risk infection; and sustained-release implants must typically be removed after their supply is exhausted. Another example is the chemotherapeutic treatment of cancer, such as breast cancer or meningiomas, which often requires large doses of highly toxic chemotherapeutic agents, such as rapamycin, bevacizumab (e.g., AVASTIN), or irinotecan (CPT-11), to be administered to the patient intravenously, which may result in numerous undesired side effects outside the targeted area.
Implantable drug-delivery devices with refillable drug reservoirs address and overcome many of the problems associated with conventional drug-delivery modalities. They generally facilitate controlled delivery of pharmaceutical solutions to a specified target, and, as the contents of the drug reservoir deplete, allow a physician to refill the reservoir in situ, i.e., while leaving the device implanted within the patient's body. However, implanted refillable drug pump devices themselves present various challenges. First, refilling is typically accomplished with a needle inserted through the septum of a fill port in the drug reservoir; this septum needs to be easily penetrable by the needle, yet must prevent leakage once the needle has been withdrawn. Further, if the refill needle is inadvertently inserted incorrectly into the device (e.g., too far, in the wrong location, with too much force, etc.), the device can be damaged. Such damage may necessitate removal of the device and its replacement with another, thereby destroying the advantage of using a refillable device in the first place. In addition, incorrect needle insertion can cause harm to the patient, e.g., if drug is accidentally injected in the tissue rather than the fill port or reservoir of the pump device.
A need exists, therefore, for improved implantable drug-delivery devices, and apparatus and methods for safely refilling such devices.